<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
	html{
		background: lightblue;
	}

		.container1{
			position: relative;
			z-index: 0;
			width: 200px;
			height: 200px;
			background: #008c8c;
		}

		.container2{
			position: absolute;
			z-index: -1;
			width: 200px;
			height: 200px;
			background: red;
			left: 100px;
			top: 100px;
		}

		.item1,.item2{
			position: absolute;
			width: 100px;
			height: 100px;
		}

		.item2{
			right: -50px;
			bottom: -50px;
			background: cyan;
		}
	</style>
</head>
<body>

	<div class="container1">
		<div class="item1" ></div>
		<div class="item2" style="background: lightsteelblue;"></div>
	</div>
	<div class="container2">
		<div class="item"></div>
		<div class="item2"  style="background: lightskyblue;"></div>
	</div>
</body>
</html>